need help choosing a levels

hi guys,
i need help choosing my A levels for college this year. im currently considering choosing:

biology
chemistry
maths
psychology OR economics

im an A grade student apart from english literature which stands at a B grade. i dont know whether to choose psychology OR economics both subjects have their pro's and con's. psycology will go really well with biology and could be a possible career path in the near future however i want to do medicine and i need a subject which will make me stand out and economics seems to be prefered and it goes really well with maths. universtities dont seem to mind however economics is prefered over psycology. i need 3 scienecs to study medicine which i have.

however this mommnet in time i need to choose the subject that could get me a potential A grade at As. any Advice?

I don't THINK your fourth A Level will matter much, especially since psychology and economics are not that differently rated. Even if you take economics you can still do any psychology degree (you only need two sciences for psychology at the top places).